1. Field
A scroll compressor is disclosed herein.
2. Background
In general, a compressor is a device that compresses a fluid, such as refrigerant gas, and may be classified into a rotary compressor, a reciprocating compressor, or a scroll compressor, for example according to a method of compressing the fluid.
The scroll compressor is a high-efficiency, low-noise compressor widely applicable in the field of air conditioners. The scroll compressor may be configured with an orbiting scroll having a wrap (hereinafter, an “orbiting wrap”) and a non-orbiting scroll (hereinafter, a “fixed scroll”) having a wrap (hereinafter, a “fixed wrap”) engaged with the orbiting wrap to perform a relative orbiting movement. Further, the scroll compressor may perform a method of forming a plurality of compression chambers including a suction chamber, an intermediate pressure chamber, aid a discharge chamber between the orbiting wrap and fixed wrap during a process in which the orbiting scroll and the fixed scroll perform a relative orbiting movement, consecutively suctioning in, compressing, and discharging a refrigerant as a volume of the plurality of compression chambers is decreased while the plurality of compression chambers continuously move in a central direction.
The scroll compressor may be divided into a dosed type in which a compression mechanism and an electric mechanism are installed together in a sealed casing, and an open type, in which a drive source is located outside of a casing and a compression mechanism operated by the drive source is installed inside of the casing.
FIG. 1 is a longitudinal cross-sectional view of an open scroll compressor according to the related art. As described herein, in the open scroll compressor according to the related art, a main frame 2 is installed in an inner space of a casing and an end of a drive shaft 3 is inserted into the main frame 2 to be rotatably coupled thereto.
An orbiting scroll 4 is coupled to an end of the drive shaft 3, and a fixed scroll 5 is coupled to the orbiting scroll 4. The fixed scroll 5 is coupled to the main frame 2 with the orbiting scroll 4 interposed therebetween. An orbiting wrap 4a and a fixed wrap 5a are formed on the orbiting scroll 4 and fixed scroll 5, respectively. The orbiting wrap 4a and fixed wrap 5a are engaged with each other to form a plurality of compression chambers (P) including a suction chamber, an intermediate pressure chamber, and a discharge chamber.
A suction portion 5b that communicates with the suction chamber and a discharge port (not shown) that communicates with the discharge chamber, are formed at one side of the fixed scroll 5 and at a center of the fixed scroll 5, respectively. The discharge port communicates with a discharge space 1b of the casing 1 whereas the suction portion 5b is connected to a suction space 1a of the casing 1, which is connected to a suction pipe.
While a first end of the drive shaft 3 is supported by the main frame 2, a second end surrounding the drive shaft 3 is supported by a sub frame 6 coupled to the main frame 2. A bearing 7 that supports the drive shaft 3 in a radial direction is installed on the bearing 7.
A balance weight 8 is provided at one side of the drive shaft 3, and a balancing space 2a is formed on the main frame 2 to accommodate the balance weight 8. The balancing space 2a is concavely formed by a predetermined depth at a lateral center of the balance weight 8 and a thrust surface 2b that supports the orbiting scroll 4 in an axial direction is formed on a lateral surface of the main frame 2 surrounding the balancing space 2a. An extended protrusion 2c that extends in a radial direction is formed at one end of an inner surface that forms the balancing space 2a to form a bottom surface of the balancing space 2a, and a bearing hole 2d is formed at a center of the extended protrusion 2c to allow the drive shaft 3 to pass therethrough.
The balancing space 2a is formed in a half-sealed type or partially-sealed to collect oil supplied to a bearing surface through an oil passage 3a of the drive shaft 3. Accordingly, a scatter hole (not shown) to scoop the collected oil in the balancing space 2a while the balance weight 8 rotates along with the drive shaft 3 is formed on an inner circumferential surface of the extended protrusion 2c or the balancing space 2a. 
A front cover 9, which forms a portion of the casing 1, is coupled to the sub frame 6, and an oil pump 10 that pumps oil stored in the casing 1 to a sliding portion and the compression mechanism is installed on the front cover 9. The oil pump 10 is coupled to the second end of the drive shaft 3, and the drive shaft 3 is coupled to a drive pulley 1 provided at an outside of the casing 1 through the front cover 9. The drive pulley 11 is selectively connected to an external drive source (not shown) driven by gas to drive the compression mechanism according to need.
Reference numeral 2e in the drawings is an axially extended portion of the main frame 2.
According to the related art open scroll compressor t, the drive pulley 11 is coupled to a drive source (not shown) to transmit an external drive force to the compression mechanism through the drive shaft 3. Then, the orbiting scroll 4 coupled to the drive shaft 3 performs an orbiting movement by an eccentric distance in a state of being supported by the main frame 2, and at a same time, a plurality of compression chambers (P) including a suction chamber, an intermediate pressure chamber, and a discharge chamber formed between the orbiting wrap 4a and the fixed wrap 5a are consecutively formed. The plurality of compression chambers (P) move to a center due to a continuous orbiting movement of the orbiting scroll 4, and as a volume is decreased refrigerant introduced into the suction space 1a of the casing 1 is consecutively suctioned in, compressed, and then discharged to the discharge space 1b. 
During this process, the oil pump 10 generates a pumping force while being rotated by the drive shaft 3, and oil collected at a lower half portion of the suction space 1a of the casing 1 is pumped by the pumping, force, and supplied to each sliding portion and the compression mechanism through the oil passage 3a of the drive shaft 3. Then, a portion of the oil supplied between the orbiting scroll 4 and the drive shaft 3 through the oil passage 3a flows down and is collected into the balancing space 2a. The oil is suctioned up through the scatter hole (not shown) when the balance weight 8 rotates along with the drive shaft 3 and moves into the suction space 1a of the casing 1 and then is circulated by the oil pump 10.
However, the foregoing open scroll compressor according to the related art draws oil introduced into the balancing space 2a to the balance weight 8 and discharges it out of the balancing space 2a, but when the balance weight 8 is continuously agitated with oil or an amount of oil introduced into the suction space I a of the casing 1 is high, the oil within the suction space la overflows and is collected in the balancing space 2a, thereby causing a problem of increasing agitation loss, as well as increasing compressor noise.
Further, according to the related art open scroll compressor, the balancing space 2a is formed at a center side rather than in the trust surface 2b of the main frame 2, and thus the thrust surface 2b of the main frame 2 is formed away in a radial direction, from an axial center of the drive shaft 3, and due to this, a supporting force at a central portion of the orbiting scroll 4 forming a relatively high pressure portion is weakened, thereby causing a problem of aggravating axial leakage when the central portion of the orbiting scroll 4 is released from the fixed scroll 5. Furthermore, according to the related art open scroll compressor, the axially extended portion 2e extends in a lengthwise manner in a backward direction (in a direction of the drive pulley 11) of the main frame 2, thereby causing a problem of increasing a size of the main frame 2 made of a relatively heavy casting compared to the sub frame 6, as well as increasing total weight of the scroll compressor.
In addition according to the related art open scroll compressor, a portion of a front end of the balance weight 8 is coupled to the main frame 2 in a butt shape, though the sub frame 6 is coupled between the main frame 2 and the front cover 9, thereby causing a problem of deteriorating a centering operation of the sub frame 6. Also, according to the related art open scroll compressor, a portion at which the main frame 2 is coupled to the sub frame is fastened by a bolt (B); however, as the bolt (B) is fastened in a direction of the main frame 2 from the sub frame 6 a step surface 6a capable of supporting a bolt head should be provided at a side of the sub frame 6, thereby causing a problem of increasing an outer diameter of the sub frame 6, as well as increasing an outer diameter of the compressor.